#43 Use categorical variable to color scatterplot | seaborn

Once you understood how to make a basic scatterplot with seaborn and how to custom shapes and color, you probably want the color corresponds to a categorical variable (a group). This is possible using the hue argument: it’s here that you must specify the column to use to map the color.

Map a color per group

# library & dataset
import seaborn as sns
df = sns.load_dataset('iris')

# Use the 'hue' argument to provide a factor variable
sns.lmplot( x="sepal_length", y="sepal_width", data=df, fit_reg=False, hue='species', legend=False)

# Move the legend to an empty part of the plot
plt.legend(loc='lower right')

#sns.plt.show()

Map a marker per group

# library & dataset
import seaborn as sns
df = sns.load_dataset('iris')

# give a list to the marker argument
sns.lmplot( x="sepal_length", y="sepal_width", data=df, fit_reg=False, hue='species', legend=False, markers=["o", "x", "1"])

# Move the legend to an empty part of the plot
plt.legend(loc='lower right')

#sns.plt.show()

Use another palette

Several palettes are available, for example: deep, muted, bright, pastel, dark, colorblind. See a complete list here TODO

# library & dataset
import seaborn as sns
df = sns.load_dataset('iris')

# Use the 'palette' argument
sns.lmplot( x="sepal_length", y="sepal_width", data=df, fit_reg=False, hue='species', legend=False, palette="Set2")

# Move the legend to an empty part of the plot
plt.legend(loc='lower right')

#sns.plt.show()

Control color of each group

# library & dataset
import seaborn as sns
df = sns.load_dataset('iris')

# Provide a dictionary to the palette argument
sns.lmplot( x="sepal_length", y="sepal_width", data=df, fit_reg=False, hue='species', legend=False, palette=dict(setosa="#9b59b6", virginica="#3498db", versicolor="#95a5a6"))

# Move the legend to an empty part of the plot
plt.legend(loc='lower right')

#sns.plt.show()

Note that this online course offers a whole chapter on seaborn. It might help you if you are a Seaborn newbie.